Now that I have Leopard, when I save an Excel file as tab delimited and then
go to open the new .txt file, I get a sylk: file format not valid error
message.
I can't reproduce this.
By any chance, does your text file start with the letters "ID", followed
by a tab?
That is how SYLK files begin, and how XL will interpret any Text file
beginning that way.
Rather than *opening* such a file, you can use Data/Get External
Data/Import Text File instead.